what happened in dallas? the assassination of john f. kennedy today at 7:30 p.m. eastern and pacific. >> truman had two big puzzles in his life. the first was, this was a man who got into politics having failed at many businesses as a young man. the only way to get into politics in missouri was to be part of a machine. there were two machines. he hooked up with the pendergast machine, which was the most corrupt and often vicious machine. i said to myself, how did this happen? how could he possibly work in this machine in local politics? that was the first thing i had to work out. the second is what we all know about. how does he come to use the atomic bomb? what was behind the decision? what is the story about the atomic bomb before he became president and then when the decision was on his desk? it is still a controversial story. i wanted to know more about it. >> from his early life through his presidency, a look at the early life of president truman tonight at 8 p.m. on c-span's "q & a." host: joining us from new york is justin ruben, the executive director of m